1. FIELD OF SEARCH
This invention relates to an improved pressure operated water level control device and to an improved temperature responsive piston and cylinder unit for such a control device or the like.
2. PRIOR ART STATEMENT
It is well known to provide a pressure operated water level control device having a movable selector means for selecting different water level settings thereof.
It is also well known to provide a temperature responsive piston and cylinder device or other heat motor means for controlling various devices when the heat motor means is activated.
For example, see the following five U.S. Patents:
U.S. Pat. No. 3,127,104--Puster PA0 U.S. Pat. No. 3,341,119--Tyler PA0 U.S. Pat. No. 3,359,387--Rhodes PA0 U.S. Pat. No. 3,386,655--Willson PA0 U.S. Pat. No. 3,880,229--Caldwell
The above patent to Rhodes, U.S. Pat. No. 3,359,387, discloses a pressure operated water level control device having movable selector means for selecting different water level settings thereof.
The patent to Puster, U.S. Pat. No. 3,127,104 and the patent to Caldwell, U.S. Pat. No. 3,880,229 each provides a temperature responsive piston and cylinder unit which extends its piston when the unit is heated and is adapted to retract its piston when cooled, the patent to Puster controlling an engine radiator valve construction with the temperature responsive unit and the patent to Caldwell controlling a a building duct damper with its respective unit.
The patent to Willson, U.S. Pat. No. 3,386,655 provides an electrically operated heat motor for changing the effective control setting of an oven temperature control device to cut back a high cooking temperature setting of the selector means to provide a low temperature non-cooking operation after a preselected time period.
The patent to Tyler, U.S. Pat. No. 3,341,119 provides an electrically operated heat motor means for unlocking a movable part of an oven control device so the control device will provide a lower temperature setting from the initial high temperature setting of the selector means thereof after the occurence of an event.
It was suggested by others that it would be desirable to provide a pressure operated water level control device which would automatically return to a low water level setting thereof after the completion of a washing operation of the washing machine utilizing such device so that during a subsequent use of the washing machine, it would require the operator to set the water level control device at a higher water level setting if such higher water level setting was desired. Thus, a mistake of providing a high water level setting for only a small load would not be made merely because the water level control device had been previously set for the highest water level setting for a previous wash load. In this manner, it was believed that an energy savings would be provided by such a unit.